1. Field of the Invention
This invention relates to a vibration preventing apparatus suitably used as an engine mount or a bushing in a vehicle etc., for example.
2. Discussion of the Related Art
Conventionally, when an engine unit to be installed to a vehicle is mounted onto a vehicle body, it is supported in a vibration prevented state via a vibration preventing apparatus such as an engine mount etc. Thus, the vibration preventing apparatus reduces or damps transmission of the vibration generated by the engine unit to the vehicle body. One example of the engine mount is shown in FIGS. 4 and 5.
This engine mount is comprised of an inner member 5 formed into a pipe shape, a rubber elastic body 6 including a body portion 61 and a pair of stopper portions 62, 62, an mounting member 7 including a tubular portion 71, and an elastic stopper 8.
In detail, the tubular body portion 61 of the rubber elastic body 6 is fixed to an outer peripheral surface of the inner member 5 integral therewith and having two cavities 63, 64 penetrating the body portion 61 axially, and the paired stopper portions 62, 62 are protruded radially outwardly and extended circumferentially from both axial ends of the body portion 61. The tubular portion 71 of the resin mounting member 7 is formed on an outer peripheral surface of the body portion 61 of the rubber elastic body 6 by an inject-forming (molding), and is adhered at each of end surfaces thereof to each of inner end surfaces of the stopper portions 62, 62. The elastic stopper 8 is fixed on an inner peripheral surface of the tubular portion 71 of the mounting member 7 and positioned in a cavity 63 to oppose to the inner member 5.
This engine mount is normally produced as explained below. In the first embodiment, the rubber elastic body 6 and the elastic stopper 8 are vulcanized and formed together with the inner member 5, and an adhering process is performed at a predetermined portion of a vulcanizedly formed body. Then, the vulcanizedly formed body is disposed in a resin forming mold for molding the mounting member 7, and a resin material is inject-molded onto an outer peripheral surface of the body portion 61 of the rubber elastic body 6 to form the mounting member 7. Thus, the mounting member 7 including the tubular body 71 is formed. Here, an inner peripheral surface of the tubular body 71 is adhered to the outer peripheral surfaces of the body portion 61 of the rubber elastic body 6 and the elastic stopper 8, and both end surfaces of the tubular portion 71 are adhered to inner side surfaces of the stopper portions 62, 62. In this way, the engine mount shown in FIGS. 4 and 5 is produced.
The engine mount thus produced is fixed at one of the inner member 5 and the mounting member 7 to the engine unit and is fixed at the other of them to the vehicle body for use so that the elastic stopper 8 positions in a main vibration inputting direction directed in the radial direction.
When the vibration is inputted from the engine unit to the engine mount, the body portion 61 of the rubber elastic body 6 disposed between the inner member 5 and the tubular portion 71 of the mounting member 7 elastically deforms to damp the vibration effectively. Here, in the case where the large vibration is inputted to the engine mount in the radial direction, the elastic stopper 8 regulates an excessive relative radial shift between the inner member 5 and the mounting member 7. On the other hand, in the case where the large vibration is inputted to the engine mount in the axial direction, the stopper portions 62, 62 disposed between end surfaces of the tubular portion 71 and a mating members (not shown) elastically attenuates a collision therebetween, so that excessive relative axial shift between the inner member 5 and the mounting member 7 is regulated. In this way, the satisfactory durability of the rubber elastic body 6 is secured by the excessive deformation prevention of the body portion 61.
By the way, in the conventional engine mount, each of the paired stopper portions 62, 62 provided at both axial ends of the rubber elastic body 6 has a small thickness in the axial direction, and therefore is unstable so as to easily fall down in the axial direction in the stage where the rubber elastic body 6 and the elastic stopper 8 are vulcanizedly formed together with the inner member 5. Accordingly, when the rubber elastic body 6 and the elastic stopper 8 are set in the resin forming mold and form the mounting member 7 by inject-molding, the stopper portions 62, 62 set in the resin forming mold may fall down. If such fall-down of the stopper portions 62, 62 occurs, a problem may be caused, i.e. the end surfaces of the forming tubular portion 71 and the stopper portions 62, 62 will not be adhered together in the desired condition. Especially, when a pour-in pressure of the resin forming material in the inject-molding step is insufficient, a bad adhesion between the end surfaces of the tubular portion 71 and the stopper portions 62, 62 becomes remarkable.
In view of the above, as one means for preventing the bad adhesion, a resin pour-in port of the resin forming mold for performing the inject-molding of the mounting member 7 is disposed between the both stopper portions 62,62 to generate an outward resin flow. Such resin flows may press the stopper portions 62, 62 onto an inner surface of the resin forming mold. However, by taking strength of the forming mounting member 7 into consideration, the resin pour-in port is selected at the position so that a weld portion of the mounting member 7 having the weakest strength (position where the poured in and flowing resin circumferentially joins) corresponds to the part of the engine mount to which the smallest vibration is inputted. That is, the resin pour-in port is selected so that the weld portion is shifted from the main vibration inputting direction in the circumferential direction. For this reason, if the resin pour-in port is disposed between the both stopper portions 62, 62, there may arise problems that position of the stopper portions 62, 62 is restricted, or circumferential length of the stopper portions 62, 62 is unnecessarily elongated.
On the other hand, the axial dimension (thickness) of each of the stopper portions 62, 62 can be increased to secure stability of the stopper portions 62, 62. However, when thickness of each of the stopper portions 62, 62 is increased outwardly, axial distance between the outer side surface of the stopper portion 62 and the mating member is decreased by a part or mount corresponding the increased part or mount of the stopper portion 62. As s result, abutment between each of the stopper portions 62,62 and the mating member occurs earlier when the large axial vibration is inputted into the engine amount, which deteriorates the riding feeling of the passenger.
Also, when thickness of each of the stopper portions 62, 62 is increased inwardly, an axial length of the tubular portion 71 is decreased corresponding to the thickness increase of the stopper portions 62. As a result, not only the strength decrease of the tubular portion 71 is introduced but the durability deterioration of the rubber elastic body 6 due to increase of the relative radial shifted amount between the inner member 5 and the mounting member 7 is caused.
The present invention is made in view of the above circumstances, and has the subject matter to provide a vibration preventing apparatus having a structure in which influences to stopping function of the stopper portion and to strength of the tubular portion etc. are small, and which is convenient to secure stability of the stopper portion in forming the mounting member by the inject-forming, in an allowable mounting space.
In order to overcome subject matter, the vibration preventing apparatus of the present invention is comprised of an inner member, a rubber elastic body including a tubular body portion fixed to an outer peripheral surface of said inner member integrally and a stopper portion provided at least one end of the body portion to protrude radially outwardly and to extend circumferentially, and a mounting member made of a resin and including a tubular portion formed by an inject-molding on an outer peripheral surface of the body portion of said rubber elastic body.
The stopper portion of said rubber elastic body has an inside protruded portion protruded from end surface of the tubular portion of the mounting member axially inwardly, and the tubular portion of the mounting member has at an inner peripheral of the end surface a step-like concave portion concaved radially inwardly to receive the stopper portion of said rubber elastic body.
According to the present invention, the stopper portion of the rubber elastic body has the inside protruded portion protruding inwardly over an end surface of the tubular portion of the mounting member and being contained in a step-like concave portion formed at the end surface of the tubular portion. This inside protruded portion increases the axial dimension (thickness) of the stopper portion and makes the stopper portion stable. In this way, when the rubber elastic body etc. are disposed in the resin forming mold and the mounting member is formed by the inject-molding, the stopper portion can be set at the predetermined position of the resin forming mold in the stabilized condition.
As a result, the tubular portion (step-like concave portion) of the mounting member formed by the inject-molding and the stopper portion (inside protruded portion) can be adhered satisfactorily. Also, on account of stabilization of the stopper portion when the rubber elastic body etc. are set in the resin forming mold, the disposing position of the resin pour-in port needs not be coincided with position of the stopper portion, whereby the stopper portion can be disposed at the suitable position by the suitable size (circumferential length).
In addition, the stopper portion of the rubber elastic body is adhered at the inside protruded portion thereof to a surface of the step-like concave portion of the tubular portion of the mounting member, in other words, an mount end portion of the stopper portion (the position where the outer peripheral surface of the stopper portion crosses with the end surface of the body portion of the mounting member) which is the easiest to be peeled off from the tubular portion in the adhesion of the stopper portion to the tubular portion is located at position spaced from the inside surface of the stopper portion (inside surface of the inside protruded portion) outwardly. Consequently, the adhering responsibility between the stopper portion and the tubular portion increases. Thus, the stopper portion can exercise the stopper function stably.
Here, thickness of the stopper portion of the rubber elastic body of the present invention does not increase outwardly, so distance between an outside surface of the stopper portion and the opposed mating member is not shortened, and therefore the stopper function of the stopper portion is not influenced or deteriorated. Also, the axial length of the tubular portion (length between the both end surfaces of the tubular portion) of the mounting member is not changed, large strength decrease of the tubular portion is not caused, or durability deterioration of the rubber elastic body due to the change of relative axial shifted amount between the inner member and the mounting member is not caused.
According to the vibration preventing apparatus of the present invention, the influences to stop the function of the stopper portion of the rubber elastic member and to strengthen the tubular portion of the mounting member can be made small, and stability of the stopper portion in forming the mounting member by the inject-molding step can be secured, in an allowable mounting space.
The present invention can have the following embodiments or formations.
The inner member is positioned at a central portion of the vibration preventing apparatus of the present invention, and is mounted to one of two members. Here, when the vibration preventing apparatus is the engine mount, the inner member is mounted on an engine unit or a vehicle body for use. The inner member can have a pipe shape and can be formed by a metal.
The body portion of the rubber elastic body can have one or more cavities penetrating the body portion axially. In providing two cavities, they can be disposed at opposite sides of the inner member in the radial direction. The stopper portion(s) can be provided at one end or both ends of the body portion, and can be disposed in an arch shape on a part of both end portions of the body portion. The inside portion of the stopper portion can protrude from an inside surface of the stopper portion axially inwardly by an outer diameter either the same as or different from an outer diameter of the stopper portion.
The mounting member is mounted onto the other of the above two members, and mounted on the vehicle body or the engine unit for use when the vibration preventing apparatus is the engine mount. The mounting member can be joined to the inner member in the inject-molding and the rubber elastic body formed integrally. The step-like concave portion(s) of the tubular portion desirably has a complementary shape with shape of the inside protruded portion of the stopper portion, and can be formed by removing an circumferential periphery of the inner portion at one end or both ends of the tubular portion by a predetermined length in the radial and axial directions.
Also, an elastic stopper can be disposed between inner member and the mounting member to prevent excessive deformation of one or both of them in the radial direction. Here, the elastic stopper can be disposed in the cavity formed in the rubber elastic body.